1. Technical Field
The embodiments described herein relate to a semiconductor memory apparatus, and more particularly, to a non-volatile semiconductor memory apparatus.
2. Related Art
Phase change random access memory (PRAM) devices have attracted attention for use as non-volatile memories because of there characteristics of non-volatility and random data access functionality. The PRAM device uses a phase change material whose state is changed to either a crystal state or an amorphous state while the phase change material is cooled down after being heated, thereby storing data. A reversible phase change of a variable resistor (GST) of the PRAM is made by Joule heating through an externally supplied electrical pulse. In particular, in order to write data, an electrical pulse needs to be supplied for a predetermined period of time (for example, 100 ns). Accordingly, since the entire operational speed of the PRAM device is slower than the operational speed of a general dynamic random access memory (DRAM) device, the PRAM device is disadvantageous for high-speed operations.